The broad goal of this proposal is to understand mechanisms for regulating excitatory synaptic transmission in the brain. Neurological diseases, including mental retardation, autism, epilepsy, and ataxia, are caused by the disruption of neural circuits in the brain. Neural circuits consist of neurons that communicate with each other at synapses through neurotransmitters. The most abundant excitatory neurotransmitter in the brain is glutamate. Glutamate acts on three classes of ionotropic glutamate receptors, AMPA-, NMDA- and kainate-type receptors. AMPA receptors mediate fast synaptic transmission, whereas NMDA receptors modulate synaptic plasticity. However, the physiological roles of kainate receptors remain unclear. We have recently identified a novel transmembrane protein, NETO2 that interacts with the kainate receptor, using an unbiased proteomic screen. In heterologous cells and neurons, NETO2 modulates the channel properties of kainate receptors, and kainate receptors, in turn, modulate NETO2 trafficking. However, there are several unanswered questions to reveal roles of kainate receptors in the brain. 1. How does NETO2/kainate receptor complex assemble and traffic to the cell surface 2. How do NETO2 and kainate receptors modulate each other? 3. How does NETO2/kainate receptor complex mediate the synaptic transmission? In this proposal, we will address these questions to reveal functional roles of kainate receptor/NETO2 complex in the brain. We will identify protein assembling order of kainate receptor/NETO2 complex and mechanisms for surface trafficking using various transgenic mouse model. We will also examine structure and functional analysis of NETO2 and kainate receptors using Xenopus laevis oocyte as a model system. Furthermore, we will reconstitute kainate receptor mediated synaptic transmission in neurons to reveal roles of kainate receptors in excitatory synaptic transmission with electrophysiological experiments. These studies will provide fundamental insights into the mechanisms that regulate synaptic transmission at excitatory synapses regards to roles of neural circuits in the brain. Because potential roles of kainate receptors in several neurological diseases including autism, schizophrenia, epilepsy and altered sensory transduction have been proposed, this work will identify novel targets for drug discovery.